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1. Set the C3835/ARC54 to 50 MHz
as shown in figure 3, perform the following test.
and the function selector to HOME, the squelch
Using a 30 MHz signal modulated 10 kHz at
switch to CARR. Adjust the signal generator for
1000 Hz set the signal generator output level for
zero output at 50 MHz. Set the two adjustable
zero output. Adjust the "SQ-ADJ" control for
attenuators to 6 db. Increase the signal generator
minimum sensitivity (fully clockwise) and slowly
output until a "flag down" condition is observed
increase the signal generator output level until
on the Indicator ID48. The signal level required
the receiver is unsquelched. The receiver shall
for "flag down" condition shall not exceed 4.8
unsquelch between 1.0 uv and 6.0 uv. Set the
signal generator output level for zero output. Ad-
just the "SQ-ADJ" control for maximum sensi-
2. Set the signal generator attenuator to
tivity (fully counterclockwise). Under this condi-
50 MHz and the RF ATTENUATOR to 120 micro-
tion, the receiver shall be unsquelched as indi-
volt and unbalance the adjustable pads by 1.0
cated by the presence of background noise, at the
db. Fine tune the signal generator for a maximum
audio output terminals. The receiver shall be con-
deflection of the vertical needle. Re-balance the
sidered squelched when the audio output is 30 db
attenuators to 6.0 db each. The needle shall be
(0.078 volts) below the 41.6 milliwatt (250 Vrms)
centered or within 1.2 dot width either side of
level across the volume control when adjusted for
center or plus or minus 10 microamps. If not,
full volume. Readjust the squelch potentiometer
adjust R227 on the homer needle to center the
on the receiver-transmitter front panel for a 1
needle. The limits for homing zero inclination
microvolt reading on the signal generator.
shall be 0.0 plus or minus 10 microamps. This re-
(d) Tone squelch test. (This test shall be
quirement shall also be met at one frequency in
conducted only when the "TONE" mode of opera-
each of the following ranges: 30.00 MHz to 33.95
MHz and 67.00 MHz to 69.95 MHz. Any readjust-
tion is specified.) Under standard conditions of
ment of R227 at other than 50 MHz shall be re-
(1) above and with the test set up as shown in
checked at 50 MHz for a compromise reading.
figure 4, perform the following tests:
1. Set the signal generator OPERATION
3. With an input of 120 microvolt from
switch to EXT MOD, and RF ATTENUATOR
the signal generator set the left pad at 3 db and
MICROVOLTS to minimum.
the right pad at 6 db, the course indicator shall
2. Set the audio oscillator output level
deflect to the left. Set the left pad at 6 db and
the right pad at 3 db, the course indicator shall
control for reading on the signal generator DE-
deflect to the right. The vertical needle deflection
VIATION meter of 3 kHz.
shall be between the first and second dots on the
3. Slowly increase setting of the signal
horizontal scale of the ID48 indicator or 138
microampere 10 percent. If necessary, adjust
(maintain redline adjustment of RF SET TO
R224 to obtain the desired deflection.
LINE adjust) until the receiver is unsquelched,
at an input of 1.2 microvolt or less.
4. Set the two adjustable attenuators to
6 db and verify that the needle is centered within
4. Set the signal generator RF ATTEN-
dot, if the needle is not within dot adjust
UATOR MICROVOLTS to 120, adjust for 2.5
R-227 for center.
kHz deviation, and set the audio oscillator main
5. Set one adjustable attenuator to 3 db
tuning dial to 145 Hz. Set the signal generator
and the other attenuator to 6 db. Under this con-
OPERATION switch to MOD OFF and note that
dition and for all values a signal input level of 12
receiver squelches as indicated by a sharp de-
microvolt to 10,000 microvolt from the signal
crease in reading on the VTVM. Set the signal
generator, the vertical needle shall deflect at least
g e n e r a t o r OPEPATION switch to EXT MOD
to the wing tip of the ID48 indicator or at least
and verify that the receiver unsquelches. The re-
90 microampere on the horizontal scale, Change
ceiver shall squelch with the modulation off and
the attenuator settings from 3 db to 6 db and 6 db
unsquelch with the modulation on.
to 3 db respectively. The vertical needle deflection
5. Set the audio oscillator main tuning
shall be in the opposite direction. This require-
dial to 155 Hz (maintain 2.5 kHz deviation and
ment shall also be met at one frequency in each
note the same results as in 4 above).
of the following ranges: 30.00 MHz to 33.95 MHz
(e) Homing test. (These tests are to be per-
and 67.00 MHz to 69.95 MHz.
formed with the signal generator modulation
"OFF"). Under standard conditions of (1) above
When Indicator ID1351A is used and
and using the test set up as in figure 5, perform
correct response to left and right indica-
the following tests:

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